Pretreatment of authentic industrial dye wastewater with zero-valent iron (ZVI) was evaluated using a bench-scale integrated anaerobic-aerobic (ZVI-AO) biological treatment system. Average ADMI (American Dye Manufacturers’ Institute) value of dye wastewater was reduced from 245 to 107 units with ZVI column pretreatment. Subsequent treatment of ZVI column effluent by a continuous AO process further reduced the ADMI values to 18-39, resulting in overall decolorization efficiency of 78-89%. A control AO system without ZVI pretreatment, which was operated in parallel, achieved just 44-69% of ADMI removal efficiency. In addition, the ZVI integrated system yielded effluents with much lower COD and BOD concentrations than the control system. The aerobic batch respiration tests confirmed that ZVI treatment transformed the recalcitrant dye compounds to slowly biodegradable fractions, thus enhancing the overall biodegradability of dye wastewater.
Vanrolleghem PA, Spanjers H, Petersen B, Ginestet P, Takacs I, Water Sci. Technol., 39(1), 195, 1999
Yu JJ, Gu GW, Esposito G, Fabbricino M, Wang SP, Sun LP, Environ. Technol., 31(11), 1191, 2010
Dircks K, Pind PF, Mosbæk H, Henze M, Water SA, 25(1), 69, 1999
Allen W, Prescott WB, Derby RE, Garland CE, Peret JM, Saltzman M, in Proceedings of 28th Ind. Waste Conference, Purdue Univ., Eng. Ext. Ser. No. 142, 661 (1973).
American Public Health Association, American Water Works Association, Water Environment Federation, Standard Methods for the Examination of Water and Wastewater, 22nd Ed., Washington, D.C. (2012).